The terms “air/vacuum”, and ““vacuum/air” and “air/vacuum stream”, etc. are used synonymously and interchangeably herein to denote a moving stream of air, at sub-atmospheric pressure, drawn by a vacuum pump. Such moving “air/vacuum” streams are conventionally used to convey granular plastic resin material in facilities in which the granular plastic resin is molded or extruded into finished or semi-finished plastic parts.
“Receiver” is a term used in the plastics industry to denote devices that temporarily hold granular plastic resin material before that granular plastic resin material is loaded into a hopper for subsequent processing by a compression or injection molding press or an extruder. As used herein, the term “process machine” denotes collectively such compression molding machines, injection molding machines and extruders.
Receivers typically include a vacuum chamber that effectively pulls granular plastic resin material into the receiver due to the vacuum that exists within the vacuum chamber. A vacuum pump is connected to the receiver to create the vacuum required within the vacuum chamber to pull granular plastic material into the receiver. This facilitates moving the granular plastic resin material from a remote location to a hopper, to be fed by the receiver, with the hopper being typically located over a process machine. The receiver and the vacuum pump are typically part of a larger resin conveying system that conveys the granular plastic resin from a supply to the receiver.
Receivers may be located over surge bins or over other temporary storage units in addition to hoppers.
Receivers load in cycles. Specifically, the receiver loads with granular plastic resin material and then dumps the granular plastic resin material as one operating cycle. Accordingly, the receiver requires some sort of a collection bin or surge hopper below the receiver to receive the granular plastic resin material as it is fed to the process machine.
Typically the vacuum source is remote, namely it is not integrated into the receiver itself. The receiver, in its most simple, elementary form, is a simple chamber that has a vacuum line connected to it to pull air from the chamber to create a vacuum inside the chamber. The vacuum then draws granular plastic resin material into the chamber portion of the receiver. The receiver accordingly has a material line connected to it for granular plastic resin material to flow in or, more accurately, to be pulled in by the vacuum, into the chamber portion of the receiver. The receiver typically has a valve or gate at the bottom of the receiver to allow the granular plastic resin material to drop out of the bottom of the receiver when the vacuum is broken or removed or when the valve or gate is otherwise opened electrically or pneumatically. Since the receiver has a storage area with a relatively large volume and cross-sectional area relative to the conduit through which the air/vacuum and granular material mixture travels, when the mixture reaches the receiver storage area, speed of the moving air/volume stream drops. The kinetic energy of the stream is no longer sufficient to carry the granular resin, so the resin falls to the bottom of the receiver.
All known receivers have these characteristics in common.